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Abstract
INTRODUCTION Didanosine is an adenosine analog, part of the nucleoside reverse-transcriptase inhibitor family. Since the description of didanosine-induced retinopathy in the early 1990s, little is known about the progression of this toxic retinopathy and the putative underlying mitochondrial defect. OBJECTIVES We report long-term follow-up for cases of didanosine-induced retinopathy and discuss a new hypothesis for pathophysiology based on the alteration of endogenous adenosine on the photoreceptor outer segment turnover and phagocytosis by the retinal pigment epithelium. METHODS Ophthalmic data from six cases (12 eyes) of didanosine-induced retinopathy from a single institution were retrospectively analyzed. RESULTS All patients displayed bilateral retinal alterations in the mid-periphery. Despite didanosine discontinuation, patients with advanced areas of patchy chorioretinal atrophy appeared to have a faster progression than those with limited lesions. Full-field electroretinogram revealed generalized rod-cone dysfunction in most cases that remained stable over time. CONCLUSION We propose new guidelines including early screening and long-term observations.
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Affiliation(s)
- Céline Faure
- Unité d'électrophysiologie, Centre Hospitalier National des Quinze-Vingts, Paris, France.,Hôpital Privé Saint Martin, Département d'ophtalmologie, Ramsay Générale de Santé, Caen, France
| | - Maxime Chassery
- Unité d'électrophysiologie, Centre Hospitalier National des Quinze-Vingts, Paris, France
| | - Raphaëlle Ores
- Unité d'électrophysiologie, Centre Hospitalier National des Quinze-Vingts, Paris, France
| | - Isabelle Audo
- Unité d'électrophysiologie, Centre Hospitalier National des Quinze-Vingts, Paris, France.,INSERM-DHOS CIC1423, CHNO des Quinze-Vingts, DHU Sight Restore, Paris, France.,Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
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Dasanu CA, Alvarez-Argote J, Goff CB. Selecting appropriate therapy for hairy cell leukemia: current state and future prospects based on molecularly defined characterization. Expert Opin Pharmacother 2022; 23:1239-1241. [PMID: 35703589 DOI: 10.1080/14656566.2022.2089561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Constantin A Dasanu
- Lucy Curci Cancer Center, Eisenhower Health, Rancho Mirage, CA, USA.,University of California in San Diego Health System, San Diego, CA, USA
| | | | - Catherine B Goff
- Department of Internal Medicine, Eisenhower Health, Rancho Mirage, CA, USA
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Abstract
INTRODUCTION Purine analogs made dramatic improvements for patients with hairy cell leukemia (HCL), but patients often relapse, require multiple treatments, and may become refractory. Major developments in treatment of relapsed/refractory HCL occurred with discovery of disease biology. New agents increase the complexity of clinical decision-making. AREAS COVERED Anti-CD22 recombinant immunotoxin Moxetumomab Pasudotox (Moxe), CD20 Mabs rituximab and obinutuzumab, BRAF/MEK inhibitors vemurafenib and dabrafenib-trametinib, and Bruton's tyrosine kinase (BTK) inhibitor ibrutinib have been tested in HCL. All show efficacy but with different treatment durations and response rates, including for eradicating minimal residual disease (MRD). Side effects differ and must be considered when selecting treatment. Studies from PubMed indexed papers and abstracts presented at major international conferences are included. EXPERT OPINION Rituximab with either purine analog or BRAF-inhibitor achieves high rates of MRD-free complete remission (CR). Moxe achieves MRD-free CR without chemotherapy toxicities. Moxe should be considered prior to splenectomy or development of adenopathy. BRAF/MEK inhibition and ibrutinib are effective options but most patients remain MRD+, requiring indefinite treatment or rituximab to prevent relapse. Under investigation is MRD elimination with CD20 antibody combined with Moxe or BRAF inhibitor. High-risk diseases including HCL variant and IGHV4-34+ unmutated HCL require further investigation.
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Affiliation(s)
- Dai Chihara
- Medical Oncology Service, Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda, MD, USA
| | - Robert J Kreitman
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health , Bethesda, MD, USA
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Abstract
Hairy cell leukemia (HCL) is an indolent B-cell malignancy, with long-term responses to purine analogs, but with decreasing efficacy and increasing toxicity with repeated courses. Leukemic cells express CD22, CD20, CD25, tartrate-resistant acid phosphatase (TRAP), annexin 1A (Anxa1), and BRAF V600E mutation. HCLv, lacking CD25, Anxa1, TRAP, and BRAF V600E, is more aggressive and less purine analog-sensitive. A molecularly defined IGHV4-34+ variant is also resistant whether HCL or HCLv immunophenotypically. Traces of HCL cells, termed minimal residual disease (MRD), accompany most with complete remission (CR) and may cause relapse. Rituximab has limited single-agent activity, but frequent CR without MRD when combined with purine analog, albeit with chemotherapy toxicities. The anti-CD22 recombinant immunotoxin Moxetumomab Pasudotox can achieve MRD-negative CR in multiply relapsed HCL without chemotherapy toxicities and was FDA approved in 2018 as Lumoxiti. Investigational oral non-chemotherapy options also include Vemurafenib or Dabrafenib/Trametinib targeting BRAF V600E ± MEK, and Ibrutinib targeting Bruton's tyrosine kinase.
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Affiliation(s)
- Robert J Kreitman
- Medical Oncology Service and Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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Tang B, Lee HO, An SS, Cai KQ, Kruger WD. Specific Targeting of MTAP-Deleted Tumors with a Combination of 2'-Fluoroadenine and 5'-Methylthioadenosine. Cancer Res 2018; 78:4386-4395. [PMID: 29844120 PMCID: PMC6072572 DOI: 10.1158/0008-5472.can-18-0814] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/20/2018] [Accepted: 05/23/2018] [Indexed: 12/16/2022]
Abstract
Homozygous deletion of the methylthioadenosine phosphorylase (MTAP) gene is a frequent event in a wide variety of human cancers and is a possible molecular target for therapy. One potential therapeutic strategy to target MTAP-deleted tumors involves combining toxic purine analogues such as 6'-thioguanine (6TG) or 2'-fluoroadenine (2FA) with the MTAP substrate 5'-deoxy-5'-methylthioadenosine (MTA). The rationale is that excess MTA will protect normal MTAP+ cells from purine analogue toxicity because MTAP catalyzes the conversion of MTA to adenine, which then inhibits the conversion of purine base analogues into nucleotides. However, in MTAP- tumor cells, no protection takes place because adenine is not formed. Here, we examine the effects of 6TG and 2FA in combination with MTA in vitro and in vivoIn vitro, MTA protected against both 6TG and 2FA toxicity in an MTAP-dependent manner, shifting the IC50 concentration by one to three orders of magnitude. However, in mice, MTA protected against toxicity from 2FA but failed to protect against 6TG. Addition of 100 mg/kg MTA to 20 mg/kg 2FA entirely reversed the toxicity of 2FA in a variety of tissues and the treatment was well tolerated by mice. The 2FA+MTA combination inhibited tumor growth of four different MTAP- human tumor cell lines in mouse xenograft models. Our results suggest that 2FA+MTA may be a promising combination for treating MTAP-deleted tumors.Significance: Loss of MTAP occurs in about 15% of all human cancers; the MTAP protection strategy presented in this study could be very effective in treating these cancers. Cancer Res; 78(15); 4386-95. ©2018 AACR.
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Affiliation(s)
- Baiqing Tang
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Hyung-Ok Lee
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Serim S An
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Kathy Q Cai
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania
| | - Warren D Kruger
- Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.
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Yehia H, Kamel S, Paulick K, Wagner A, Neubauer P. Substrate spectra of nucleoside phosphorylases and their potential in the production of pharmaceutically active compounds. Curr Pharm Des 2017; 23:CPD-EPUB-86514. [PMID: 29076414 DOI: 10.2174/1381612823666171024155811] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 10/10/2017] [Accepted: 10/20/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND Nucleoside phosphorylases catalyze the reversible phosphorolysis of pyrimidine and purine nucleosides in the presence of phosphate. They are relevant to the appropriate function of the immune system in mammals and interesting drug targets for cancer treatment. Next to their role as drug targets nucleoside phosphorylases are used as catalysts in the synthesis of nucleosides and their analogs that are widely applied as pharmaceuticals. METHODS Based on their substrates nucleoside phosphorylases are classified as pyrimidine and purine nucleoside phosphorylases. This article describes the substrate spectra of nucleoside phosphorylases and structural properties that influence their activity. Substrate ranges are summarized and relations between members of pyrimidine or purine nucleoside phosphorylases are elucidated. RESULTS Nucleoside phosphorylases accept a broad spectrum of substrates: they accept both base and sugar modified nucleosides. The most widely studied nucleoside phosphorylases are those of Escherichia coli, mammals and pathogens. However, recently the attention has been shifted to thermophilic nucleoside phosphorylases due to several advantages. Nucleoside phosphorylases have been applied to produce drugs like ribavirin or fludarabine. However, limitations were observed when drugs show an open ring structure. Site-directed mutagenesis approaches were shown to alter the substrate specificity of nucleoside phosphorylases. CONCLUSION Nucleoside phosphorylases are valuable tools to produce modified nucleosides with therapeutic or diagnostic potential with high affinity and specificity. A wide variety of nucleoside phosphorylases are available in nature which differ in their protein sequence and show varying substrate spectra. To overcome limitations of the naturally occurring enzymes site-directed mutagenesis approaches can be used.
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Affiliation(s)
- Heba Yehia
- TU Berlin, Institute of Biotechnology, Department of Bioprocess Engineering, Ackerstr. 76, 13355 Berlin. Germany
| | - Sarah Kamel
- TU Berlin, Institute of Biotechnology, Department of Bioprocess Engineering, Ackerstr. 76, 13355 Berlin. Germany
| | - Katharina Paulick
- TU Berlin, Institute of Biotechnology, Department of Bioprocess Engineering, Ackerstr. 76, 13355 Berlin. Germany
| | - Anke Wagner
- TU Berlin, Institute of Biotechnology, Department of Bioprocess Engineering, Ackerstr. 76, 13355 Berlin. Germany
| | - Peter Neubauer
- TU Berlin, Institute of Biotechnology, Department of Bioprocess Engineering, Ackerstr. 76, 13355 Berlin. Germany
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Christopherson RI, Mactier S, Almazi JG, Kohnke PL, Best OG, Mulligan SP. Mechanisms of action of fludarabine nucleoside against human Raji lymphoma cells. Nucleosides Nucleotides Nucleic Acids 2015; 33:375-83. [PMID: 24940695 DOI: 10.1080/15257770.2013.863334] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Fludarabine (2-FaraAMP) is a purine analog that is effective against chronic lymphocytic leukemia (CLL) and non-Hodgkins lymphoma (NHL). For some cases of CLL, 2-FaraAMP as a single agent can clear the blood of leukemia cells, but leukemia stem cells usually remain protected in sanctuary sites. It is clear that 2-FaraAMP has multiple mechanisms of action that may collectively result in strand breaks in DNA, accumulation of phosphorylated p53 and apoptosis. We have demonstrated using the human Burkitt's lymphoma B-cell line, Raji, that p53, p63 and p73 all accumulate in the nucleus, following treatment of cells with fludarabine nucleoside (2-FaraA). In addition, phosphorylated p53 accumulates in the cytosol and at mitochondria. Using sophisticated methods of proteomic analysis with mass spectrometry, proteins that become differentially abundant after treatment of cells with 2-FaraA have been identified, providing considerable additional information about the cellular responses of B-lymphoid cancers to this purine analog. The levels of proteins involved in the unfolded protein response increase, indicating that endoplasmic reticulum stress is likely to be one mechanism for induction of apoptosis. The levels of a number of proteins found on the outer plasma membrane change on cells treated with 2-FaraA, suggesting that signaling from the B-cell antigen receptor (BCR) is stimulated, resulting in induction of apoptosis through the intrinsic pathway. Increased levels of the cell surface proteins, CD50, CD100 and ECE-1, would promote survival of these cells; the balance between these survival and death responses would determine the fate of the cell.
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Abelson AL, Shelton GD, Whelan MF, Cornejo L, Shaw S, O'Toole TE. Use of mycophenolate mofetil as a rescue agent in the treatment of severe generalized myasthenia gravis in three dogs. J Vet Emerg Crit Care (San Antonio) 2009; 19:369-74. [PMID: 25164637 DOI: 10.1111/j.1476-4431.2009.00433.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To describe the use of IV and oral mycophenolate mofetil (MMF) as adjunctive therapy in 3 dogs with severe generalized myasthenia gravis. CASE SERIES SUMMARY Three dogs suffering from severe generalized myasthenia gravis as confirmed by acetylcholine antibody titers were treated with MMF as part of their treatment regimens. All 3 dogs had radiographic evidence of megaesophagus and suffered from severe regurgitation. Each dog was initially treated with pyridostigmine and supportive agents. When clinical remission was not achieved, IV MMF was administered to all dogs. Signs of clinical remission were apparent within 48 hours and all dogs were later maintained on oral MMF following resolution of regurgitation. NEW OR UNIQUE INFORMATION PROVIDED This is the first report of the use of IV MMF as adjunctive treatment in dogs with severe generalized myasthenia gravis. Outcome was favorable in all 3 dogs and no adverse effects were noted from the MMF.
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Affiliation(s)
- Amanda L Abelson
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01356Department of Pathology, University of California, San Diego, La Jolla, CA 9037Department of Emergency and Critical Care, Angell Animal Medical Center, Boston, MA 02130
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